System a - 100, A-110, Doepfer – Doepfer A-110 Standard VCO User Manual
Page 5: Sine wave, Frequency modulation (fm)

doepfer
System A - 100
VCO
A-110
5
Sine Wave
Sine waves are pure waves: they just contain the
fundamental, without any harmonics (see Fig. 5). They
are thus not suitable for subtractive synthesis (shaping
sound with a filter).
Fig. 5: Spectrum of a sine wave
Frequency Modulation (FM)
Because the frequency of the VCO is controlled by the
voltages at inputs " and §, Frequency Modulation is
possible: frequency (pitch) is continuously varied by
the voltages at the CV input/s.
For instance, if the frequency of the VCO is controlled
by a slow LFO, you get typical vibrato (see Fig. 6).
Fig. 6: Frequency modulation using a slow LFO
(Vibrato)
If the modulation frequency is in the audio range,
completely different sounds emerge (see User Exam-
ples 6).
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Harmonics ➨